Vanadium containing addition agent and process for producing same



United States Patent 3,334,992 VANADIUM CONTAINING ADDITION AGENT AND PROCESS FOR PRODUCING SAME James H. Downing, Clarence, and Rodney F. Merkert, Buffalo, N.Y., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Filed Jan. 27, 1964, Ser. No. 340,498 12 Claims. (Cl. 75.5)

The present invention relates to a vanadium containing addition agent for use in the treating of steel. More particularly, the present invention relates to a vanadium and carbon containing addition agent in which the predominant proportion of combined vanadium is in the form of V C. That is, more vanadium is combined as V C than as VC.

In the manufacture of tool steels and other steels such as the high strength, low alloy structural steels, and the normal constructional steels, significant amounts of vanadium are utilized as an alloying constituent in order to provide improvement in the properties of the steel. For example, vanadium additions are widely used to provide toughness and strength, and also to aid in stabilizing steels. Moreover, the amount of vanadium used for this purpose is significantly increasing.

Up to the present time, vanadium for use as an alloy addition, has been produced as ferrovanadium which generally contains about 50 to 75% V, 0.2 to 3.0% C, 1.5% to 8.00% Si, remainder iron. The present commercial production of ferrovanadium generally involves the aluminothermic reduction of vanadium oxides and this type of processing generally results in a relatively high price for the resulting product.

Moreover, the fact that commercial ferrovanadium contains about 25 to 50% iron means that an ineffective constituent, viz. iron, accounts for a substantial proportion of the shipping costs and storage space for'the material.

In place of ferrovanadium, vanadium carbide, VC, has been proposed as an addition agent for treating steel. However, vanadium carbide, VC, has a comparatively slow solubility in molten steel and this feature, together with the relatively low proportion of contained vanadium and the relatively low strength of the material have precluded the commercial utilization of vanadium carbide as an addition agent in spite of its reduced cost.

It is accordingly an object of the present invention to provide a vanadium containing addition agent having a high proportion of vanadium.

It is another object of the present invention to provide a vanadium-containing agent having a very low oxygen content.

It is a further object of the present invention to provide a vanadium-containing addition agent having rapid solubility when added to molten steel.

It is a further object of the present invention to provide strong, dense, non friable vanadium containing addition agents in which the predominant proportion of combined vanadium is present in the form of V C.

It is another object to provide a vanadium containing addition agent which is inexpensive as compared to ferrovanadium.

In addition to the foregoing, other objects will be apparent from the following description and claims.

A vanadium-containing addition agent in accordance with the present invention is the solid state reaction product of a pressed mixture of carbon and vanadium oxide in which reaction product the predominant proportion of combined vanadium is in the form of V C and in which the oxygen content is less than 2% by weight. The vanadium and carbon constituents of the addition agent "ice ' by processing ammonium metavanadate, is blended with carbon, e.g. Thermatomic carbon and the mixture is briquetted under a pressure of about 100 to 10,000 p.s.i. while using about 1.5 to 2% Mogul 2 with about 15% to 20% water as a binder.

The sizing of V 0 in the practice of the present invention is suitably 65 mesh by down and suitable sizing for the carbon is 200 mesh by down.

The proportion of carbon used in the mixture is preferably the stoichiometric amount indicated by the following equation:

However, a range of about 1l0% of the stoichiometric amount of carbon can be suitably used.

When the mixture has been briquetted, usually in sizes of about 2" x 2" x 1 /2", the resulting agglomerates are preferably dried at a temperature from about 200 to 250 F. to remove at least about of the moisture. Higher drying temperatures are to be avoided in order to prevent oxidation of the mixture.

After drying, the briquets are charged to a vacuum furnace and preferably arranged therein on graphite slabs to avoid possible reaction with fur-nace refractories. Although the afore-described reaction tends to go to the right at atmospheric pressure and at temperatures of 1500- 1700 C. it has been found that the reaction is incomplete and the material obtained has an oxygen content of 2% or more and a carbon content of more than about 13%. On the other hand, the present invention is practiced under vacuum conditions and at a much lower temperature range of l200 C.1400 C. so that a product is produced in which the predominant proportions of combined vanadium is in the form of V C and in which the oxygen, free carbon and nitrogen contents of the product can be controlled at very low levels.

In preparing the addition agent of this invention from the aforedescribed briquets, the furnace is initially evacuated to a pressure below about 300 microns and the temperature is increased to 1200-l400 C. at a convenient rate so that the reaction proceeds and is completed at 1200-1400 C. and at a pressure of less than 300 microns.

As the reaction proceeds, starting at a threshold temperature of about 1200 C., pressure may increase in the furnace up to about 20 mm. due to evolution of CO, however, as the reaction goes to completion the CO pressure drops and when the CO pressure goes below about 300 microns the reaction is considered complete. That is, the reduction reactionis completed at a temperature of 1200-l400 C. and 300 microns pressure or less. The product obtained in this manner is in the form of strong, dense briquets containing less than 2% oxygen, and less than 0.15% nitrogen and in which the predominant proportion of combined vanadium is in the form of V C.

The product addition agent of the present invention is also characterized by being strong, non-pyrophoric and by having good solubility in molten steel.

In a further embodiment of the present invention, finely divided iron powder suitably sized from mesh by down is blended 'with V 0 and carbon prior to briquetting. The proportion of iron powder used is that which provides ranges from 2 to 10%, preferably 5% by Weight 1 Trademark of R. T. Vanderbilt C0. "Trademark of Corn Products Co.

.5 of iron in the product material. It has been found that the inclusion of iron in the material, in the proportions specified has the combined effect of markedly increasing the strength and the proportion of V C in the resulting product. The inclusion of iron has also been found to result in a reduced oxygen and nitrogen content.

In a further embodiment of the present invention, finely divided iron oxide, e.g. hematite (Fe O and/or mill scale (Fe O can be employed in place of iron powder to provide the desired iron content in the product addition agent.

In this embodiment the additional amount of carbon required to provide reduction of the iron oxide to metal is included in the briquetting mixture. A suitable sizing for the iron oxide material is 100 mesh by down.

The following examples are provided to further illustrate the present invention.

Example I A mix was prepared containing 10 lbs. of V sized 65 mesh by down, 3.2 lbs. of carbon 200 mesh by down, 0.25 lb. of Mogul and 20% water.

Briquets sized 2" x 2" x 1 /2 were prepared from the mix by pressing at 3000 p.s.i. and drying at 250 F. The resulting briquets, in the amount of 4.2 lbs. were charged to a vacuum furnace having interior working dimensions of 40" x 12" x 7".

The pressure in the furnace was reduced to 90 microns and the furnace was heated to 1385 C. Due to evolution of CO the pressure rose to 900 microns. After about 30 hours at 1385 C. the pressure dropped to 90 microns and the furnace and contents were then cooled to room temperature under a positive pressure of argon.

The product briquets, in the amount of 3.7 lbs., analyzed 12.7% combined carbon and contained 0.33% oxygen.

Example II A mix was prepared as in Example I and briquets sized 2" x 2" x 1 /2" were prepared from the mix by pressing and drying under the same conditions. The resulting briquets in the amount of 10.3 lbs. were charged to the same vacuum furnace as in Example I.

The pressure in the furnace was reduced to 60 microns and the furnace was heated to 1385 C. Due to evolution of CO the pressure rose to 900 microns. After about 18 hours at 1385 C. the pressure dropped to 60 microns and the furnace and contents were cooled to room temperature under a positive pressure of argon.

The product briquets in the amount of 5.8 lbs., analyzed 10.8% combined carbon and contained 0.2% oxygen.

Example 111 A mix was prepared having the following proportions: 400 lbs. of V 0 sized 65 mesh by down, 136 lbs. of carbon 200 mesh by down, 9 lbs. of Mogul and 20% water.

Briquets sized 2" x 2" x 1 /2" were prepared from the mix by pressing at 3000 p.s.i. and drying at 250 F. The resulting briquets in the amount of 1030 lbs. were charged to a vacuum furnace having interior working dimensions of 110" x 66" x 27".

The pressure in the furnace 'was reduced to 140 microns and the temperature was raised to 1385 C. The pressure rose to 5000 microns and after about 30 hours at 1385 C. the pressure dropped to 140 microns and the furnace and contents were cooled under a positive pressure of argon.

The product briquets, in the amount of 562 lbs., analyzed 84.76% vanadium, 12.3% combined carbon, 1.03% oxygen, and 0.03% nitrogen.

Example IV A mix was prepared having the following proportions: 50 lbs. of V 0 sized 65 mesh by down, 16.5 lbs. of carbon 200 mesh by down, 1.0 lbs. or iron powder sized mesh by down, 1.2 lbs. of Mogul and 20% by weight water.

Briquets sized 2" x 2" x 1 /2" were prepared from the mix by pressing at 3000 p.s.i. and drying at 250 F. The resulting briquets in the amount of 64 lbs. were charged to a vacuum furnace having interior dimensions The pressure in the furnace was reduced to 150 microns and the temperature was raised to 1385 C. The pressure rose to 5000 microns and after about 60 hours at 1385 C. the pressure dropped to 175 microns and the furnace and contents were cooled to room temperature under a positive pressure of argon.

The product briquets, in the amount of 31.6 lbs., analyzed 85.45% vanadium, 11.4% combined carbon, 2.16% iron, 0.28% oxygen, and 0.09% nitrogen.

Example V A mix was prepared having the following proportions: 400 lbs. of V 0 sized 6 5 mesh by down, 136 lbs. of carbon sized 200 mesh by down, 6.5 lbs. of iron powder sized 100 mesh by down, 9 lbs. of Mogul and 20% Water.

Briquets sized 2" x 2" x 1 /2" were prepared from the mix by pressing at 3000 p.s.i. and drying at 250 F. The resulting briquets in the amount of 4164 lbs. were charged to a vacuum furnace having interior working dimensions of x 66" 'x 27".

The pressure in the furnace was reduced to microns and the temperature was raised to 1385" C. The pressure rose to 12 mm. at this temperature and after about 48 hours at 1385 C. the pressure dropped to 150 microns and the furnace and contents were cooled to room temperature under positive pressure of argon.

The product briquets in the amount of 2301 lbs., analyzed 84.50% vanadium, 12.5% combined carbon, 2.01% iron, 0.30% oxygen, and 0.02% nitrogen.

Example VI A mix was prepared containing 25 lbs. of V 0 sized 65 mesh by down, 8.5 lbs. of carbon 200 mesh by down, 0.54 lb. of Fe O sized 200 mesh by down, 0.7 lb. of Mogul, and 20% water.

Briquets sized 2" x 2 x 1 /2" were prepared from the mix by pressing and drying at 250 F. The resulting briquets, in the amount of 29.1 lbs. were charged to a vacuum furnace having interior dimensions of 40" x 12" x 7".

The pressure in the furnace was reduced to 200 microns and the furnace was heated to 1385 C. Due to evolution of CO the pressure rose to 500 microns. After about 24 hours the pressure dropped to 100 microns and the furnace and contents were cooled to room temperature under vacuum.

The product briquets, in the amount of 16.8 lbs., containing approximately 2% iron analyzed 12.48% combined carbon and 0.19% oxygen.

Example VII Quantities of briquets in accordance with the present invention were made from the following basic mix order with various iron contents. In all cases, the iron addition was iron powder sized 100 mesh by down.

BASIC MIX ORDER V203 100 lbs 65 mesh by down. Oarbon. 34 lbs 200 mesh by down. Mogul 2.25 lbs- Water 20% by weight 6 furnace, due to evolution I'Qse to microns and TABLE IV. ANALYSIS OF ADDITION AGENTS OF THIS at the end of about hours had dropped to 475 microns. I V N After 18 hours at 1385" C. the pressure dropped to 125 microns and the furnace and contents were cooled to Percent A a temperature under 5 Business. 322221 $222 95; than Analysis of the product briquet in percent by weight is and Carbon shown in Table I for diiterent iron contents.

as it TABLE I 1 so 717 21 8i5 90 10 3.45:5 Fe,% o,% 0,% N,% 10 275 1 3 3 3 a 253i: ittitzttitiltttie. 10.6 0.12 0.18

0.1 0.15 0.08 8.5 0.17 0.12 It can be seen from Table III that the solution times of the addition agent of the present invention are quite rapid It can be seen from Table I that the addition agents and comparable to that of f rrovanadium and considerhaving iron contents between 2% and 10% have the lowy re rapid than for V V recoverles usmg est oxygen contents and also lower nitrogen contents the addlhon agents of the Present lhVelItlOh, f and h b i i h i without iron contents, have averaged 96.5% Whlch com- The briquets containing the diiferent amounts of iron Pares favorably With the Special grades of ferfovanediumwere also tested for compressive strength. The average re- 111 a further embodiment of he Present ihvellholi'l, a n are Shown i T bl 11 nitrified vanadium-containing addltl-on agent is provided in which the vanadium, carbon and nitrogen content con- TABLE II forms to the empirical formula V CN Fe content: Loadmg to fallure This addition agent is produced by contacting the previ- 0% 360 ously described as-pr'oduced material of the present in- 2% 460 vention with nitrogen at a temperature of 1000 C. or 5% 745 above and, before cooling, in an amount at least sufiicient 10% 693 3 to convert the V 0 in the material to V CN. The result- 15% 610 ing material satisfies the empirical formula Table II shows that iron contents from 2% to 10% 1.49 2.42 0.a5 1.20 'f Particularly 5 to e Provide Substantially and the predominant proportion of combined vanadium Increased trength W1th% bemg the strongest is in the form of V CN. This nitrided material is also The bnquets In the tests of Table II were strong, and is characterized by high density and a low 1%" X 1%" x pillows and were tested uslng standard oxygen content of less than 2%. comlimssion test. equipment having a Self-aligning The following Example VIII illustrates this embodi- Presslon head' ment of the present invention.

Table III below shows solub1llty times for addition 4 agents of the present invention and for VC and FeV Example VH1 additions. The results shown in Table are based On A mix was prepared having the following roportions: the results of solution time tests in which the addition 40 1 f 0 sized 5 mesh by down, 13 1 f agents Were used to make corresponding additions of carbon sized 200 mesh by down, 9 lbs. of Mogul, 6.5 lbs. vanadium to 100 lb. induction melted heats of aluminumf iron Powder Sized 100 mesh by down and 20% water Steel at 1600 The vanadium carbide Briquets ized 2" X 2" X 1%" were prepared from the additions Were briquets Sized X 1% X and the mix by pressing at 3000 p.s.i. and drying at 250 F. The ferrovanadium addition Was Sized 1 inch y down- The resulting briquets in the amount of 4134 lbs. were charged Vc addition Was made following the Practice of the P to a vacuum furnace having interior dimensions of ent invention except that the carbon content of the re- 0" X X 2 action mixture Was increased to Provide a Product The pressure in the furnace was reduced to 200 microns sentially in form of I and the temperature was raised to 13 85 C. The pressure TABLE III rose to 20 mm. at this temperature and after about 60 hours at 1385 C. the pressure dropped to 175 I111CIOI1S Composition Percentvanadium Average solution 55 and the carbide phase was completed. The temperature Added Time, seconds was then lowered to 1100 C. and a positive pressure of nitrogen (about 3 to 5" H O) was put on the charge for FeV 14% v Sized 1" XD) 0.5 25 2 hours and at 1000 C. for '6 hours. At the end of this 6 3 %g%g 8-? 2; period the furnace and contents were cooled under a Tni'sinventi on, 6%?6: 6O nitrogen atmosphere. Two hundred thirty-five pounds of V0 1 86 nitrogen were used and was recovered.

The product briquets in the amount of 2015 lbs. an- The densities and characteristic high V C contents of l d 781% vanadium, bo 73% it the additive agent of the present invention is illustrated 0.80% oxygen, and 2% iron. in Table IV which shows that the proportion of vanadium 65 The mesh sizes referred to in the foregoing description combined as V C in the present invention is greater than are U S i that combined as VC in all instances, and is particularly Wh t i l i d i pronounced at iron contents of more than 2% Iron con- 1. A process for producing vanadium-containing adtents of between about 3% and 10% are found to be dition agents which comprises compacting finely divided especially high in 2 This feature, high Va 70 V 0 with carbon, said carbon being at least the stoichiotent is of significant advantage as regards the solubility metric amount to reduce the V 0 and form V C but not of the addition agent in molten steel. exceeding about of stoichiometric; heating the com- The data shown in Table IV, except for density, was pact material to between about 1200 C. and 1400 C. obtained using X-ray difiraction and optical microscopy under vacuum conditions to cause reaction between said techniques. 75 carbon and said V 0 and completing the reaction at a 7 temperature of between 1200 C. and 1400 C. and at a pressure of 300 microns or less.

2. A process in accordance with claim 1 wherein the reaction product is contacted with nitrogen gas before cooling below about 1000 C., said nitrogen being in an amount suflicient to convert V C in the reaction product to 3. A process for producing vanadium-containing addition agents Which comprises compacting finely divided V with carbon and iron, said carbon being at least the stoichiometric amount to reduce the V 0 and form V C but not exceeding about 110% of stoichiometric; heating the compacted material to between about 1200 C. and 1400 C. under vacuum conditions to cause reaction between said carbon and said V 0 and completing the reaction at a temperature of between 1200 C. and 1400 C. and at a pressure of 300 microns or less.

4. A process in accordance with claim 3 wherein the reaction product is contacted with nitrogen gas before cooling below about 1000 C., said nitrogen being in an amount sufiicient to convert V C in the reaction product to VZCN.

5. A process for producing vanadium-containing addition agents which comprises compacting finely divided V 0 with carbon and iron oxide, said carbon being at least the stoichiometric amount to reduce the V 0 and iron oxide to form V C and elemental iron but not exceeding about 110% of stoichiometric; heating the compacted material to between about 1200" C. and 1400 C. under vacuum conditions to cause reaction between said carbon and said V 0 and iron oxide and completing the reaction at a temperature of between 1200 C. and 1400 C. and at a pressure of 300 microns or less.

6. A process in accordance with claim 5 wherein the reaction product is contacted with nitrogen gas before cooling below about 1000" C., said nitrogen being in an amount sufircient to convert V C in the reaction product to VZCN.

7. An addition agent for use in the manufacture of steel consisting essentially of vanadium, carbon and about 2 to 10% iron, said addition agent being at least in the form of combined vanadium and carbon and containing less than 2% oxygen, with the predominant pro portion of combined vanadium being in the form of V C and the atomic ratio of vanadium to carbon being in the range of 1.49 to 2.42.

8. An addition agent in accordance with claim 7 which contains about 2% iron.

9. An addition agent in accordance with claim 7 which contains about 5% iron.

10. An addition agent in accordance with claim 7 which contains about 10% iron.

11. An addition agent for use in the manufacture of steel consisting esentially of vanadium, carbon, nitrogen and about 2 to 10% iron, said addition agent being at least 80% in the form of combined vanadium, carbon and nitrogen and containing less than 2% oxygen, with the predominant proportion of combined vanadium being in the form of V CN, the atomic ratio of vanadium to carbon being in the range of 1.49 to 2.42 and the atomic ratio of nitrogen to carbon being in the range of 0.35 to 1.20.

12. An addition agent in accordance with claim 11 which contains about 2% iron.

References Cited UNITED STATES PATENTS 12/1961 Trifileman 23-208 OTHER REFERENCES DAVID L. RECK, Primary Examinen.

HYLAND BIZOT, Examiner.

W. W. STALLARD, Assistant Examiner. 

7. AN ADDITION AGENT FOR USE IN THE MANUFACTURE OF STEEL CONSISTING ESSENTIALLY OF VANADIUM, CARBON AND ABOUT 2 TO 10% IRON, SAID ADDITION AGENT BEING AT LEAST 80% IN THE FORM OF COMBINED VANADIUM AND CARBON AND CONTAINING LESS THAN 2% OXYGEN, WITH THE PREDOMINANT PROPORTION OF COMBINED VANADIUM BEING IN THE FORM OF V2C AND THE ATOMIC RATIO OF VANADIUM TO CARBON BEING IN THE RANGE OF 1.49 TO 2.42. 